The present invention relates to a disc drive microactuator, and more particularly to improved coil structures for use in a magnetic microactuator utilizing a vertical magnetic circuit contained on a substrate and a flex circuit to provide microactuation force.
The density of concentric data tracks on magnetic discs continues to increase (that is, the size of data tracks and radial spacing between data tracks are decreasing), requiring more precise radial positioning of the head. Conventionally, head positioning is accomplished by operating an actuator arm with a large-scale actuation motor, such as a voice coil motor, to radially position a head on a flexure at the end of the actuator arm. The large scale motor lacks sufficient resolution to effectively accommodate high track-density discs. Thus, a high resolution head positioning mechanism, or microactuator, is necessary to accommodate the more densely spaced tracks.
One promising approach for high resolution head positioning involves employing a high resolution microactuator in addition to the conventional lower resolution actuator motor, thereby effecting head positioning through dual-stage actuation. Various microactuator designs have been considered to accomplish high resolution head positioning. One design involves inserting a silicon-based thin film structure between the suspension and the slider in a disc drive assembly. A major technical challenge in implementing such a microactuator is to provide sufficiently large actuation force to overcome spring bias forces to drive the head at a speed high enough to accommodate the required bandwidth. Such a design must be realized in a relatively small wafer area, to keep costs reasonable and to allow easy integration into the disc drive design.
Therefore, there is a need in the art for a microactuator design providing large actuation force with reasonable power consumption and within a reasonable wafer area to microposition a transducing head at a speed that accommodates the high bandwidth required by high performance disc drives. One design for achieving this goal is disclosed in U.S. application Ser. No. 09/315,006, filed May 19, 1999 for xe2x80x9cMagnetic Microactuatorxe2x80x9d by P. Crane, W. Bonin and B. Zhang, which is hereby incorporated by reference. Additional improvements to such a design are desirable to further advance the state of the art.
The present invention is a microactuator for a disc drive includes a stator attached to the disc drive support structure, a rotor operatively attached to a slider, the rotor being movable with respect to the stator in a first horizontal plane generally parallel to the surface of the disc, and a vertically arranged magnetic circuit. The magnetic circuit is arranged in a plurality of planes substantially parallel to the first horizontal plane so as to move the microactuator rotor and the slider in the first horizontal plane with a stroke of at least about 2 micro-meters in response to a current of no greater than about 100 milli-Amps provided to the magnetic circuit.